The
XCreateColormap function creates a colormap of the specified visual type
for the screen on which the specified window resides and returns the colormap
ID associated with it. Note that the specified window is only used to determine
the screen.

The initial values of the colormap entries are undefined for
the visual classes GrayScale, PseudoColor, and DirectColor. For StaticGray,
StaticColor, and TrueColor, the entries have defined values, but
those values are specific to the visual and are not defined by X. For StaticGray,
StaticColor, and TrueColor, alloc must be AllocNone, or a BadMatch
error results. For the other visual classes, if alloc is AllocNone,
the colormap initially has no allocated entries, and clients can allocate
them. For information about the visual types, see section 3.1.

If alloc is
AllocAll, the entire colormap is allocated writable. The initial values
of all allocated entries are undefined. For GrayScale and PseudoColor,
the effect is as if an XAllocColorCells call returned all pixel values
from zero to N - 1, where N is the colormap entries value in the specified
visual. For DirectColor, the effect is as if an XAllocColorPlanes call
returned a pixel value of zero and red_mask, green_mask, and blue_mask
values containing the same bits as the corresponding masks in the specified
visual. However, in all cases, none of these entries can be freed by using
XFreeColors.

The XCopyColormapAndFree function creates a
colormap of the same visual type and for the same screen as the specified
colormap and returns the new colormap ID. It also moves all of the client's
existing allocation from the specified colormap to the new colormap with
their color values intact and their read-only or writable characteristics
intact and frees those entries in the specified colormap. Color values
in other entries in the new colormap are undefined. If the specified colormap
was created by the client with alloc set to AllocAll, the new colormap
is also created with AllocAll, all color values for all entries are
copied from the specified colormap, and then all entries in the specified
colormap are freed. If the specified colormap was not created by the client
with AllocAll, the allocations to be moved are all those pixels and planes
that have been allocated by the client using XAllocColor, XAllocNamedColor,
XAllocColorCells, or XAllocColorPlanes and that have not been freed
since they were allocated.

XCopyColormapAndFree can generate BadAlloc
and BadColor errors.

The XFreeColormap function deletes the association
between the colormap resource ID and the colormap and frees the colormap
storage. However, this function has no effect on the default colormap for
a screen. If the specified colormap is an installed map for a screen, it
is uninstalled (see XUninstallColormap). If the specified colormap is
defined as the colormap for a window (by XCreateWindow, XSetWindowColormap,
or XChangeWindowAttributes), XFreeColormap changes the colormap associated
with the window to None and generates a ColormapNotify event. X does
not define the colors displayed for a window with a colormap of None.

The red, green, and blue values are always in the range 0 to 65535 inclusive,
independent of the number of bits actually used in the display hardware.
The server scales these values down to the range used by the hardware. Black
is represented by (0,0,0), and white is represented by (65535,65535,65535).
In some functions, the flags member controls which of the red, green,
and blue members is used and can be the inclusive OR of zero or more of
DoRed, DoGreen, and DoBlue.

The server failed
to allocate the requested resource or server memory.

BadColor

A value
for a Colormap argument does not name a defined Colormap.

BadMatch

An
InputOnly window is used as a Drawable.

BadMatch

Some argument or pair
of arguments has the correct type and range but fails to match in some
other way required by the request.

BadValue

Some numeric value falls outside
the range of values accepted by the request. Unless a specific range is
specified for an argument, the full range defined by the argument's type
is accepted. Any argument defined as a set of alternatives can generate
this error.